Nightmare frequency linked to later psychotic episodes

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Children who often have nightmares or night terrors may be more likely to experience psychotic episodes such as hallucinations by early adolescence, a British study found.

Researchers at the University of Warwick surveyed nearly 7,000 children (and their mothers) six times until they reached age 12, asking how often the child had nightmares to the point where he or she woke up in fear or worry, or night terrors that resulted in panic and involuntary screaming.

Children who reported “regular” nightmares or night terrors were more than three times as likely to experience hallucinations, interrupted thoughts, or delusions by age 12, compared with children who reported nightmares or night terrors less frequently. Children of mothers who reported having a child who experienced frequent nightmares were up to 1½ times more likely to have a psychotic episode by age 12.

The link between nightmares or night terrors and psychotic episodes remained strong even when researchers took into account behavioral or neurological problems among some of the children.

The authors said the findings suggest that some children are unable to establish sleep and wake boundaries, which could help explain why they experience hallucinations and other psychotic episodes.

BOTTOM LINE: Children who often have nightmares or night terrors may be more likely to later experience psychotic episodes such as hallucinations.

CAUTIONS: The study relied on self-reporting by parents and children, so the results may not be accurate. The study does not specify how often the children had nightmares.

WHERE TO FIND IT: Sleep, Feb. 28

Can sleep machines harm babies’ ears?

Some ambient-sound machines designed to help infants sleep might damage their hearing, a University of Toronto study found.

Infant sleep machines are designed to produce white noise that overrides other sounds and helps a baby drift to sleep. The researchers tested the sound levels of 14 infant sound machines played at maximum volume 30, 100, and 200 centimeters away from a machine that modeled a 6-month-old’s ear canal. When tested 30 and 100 centimeters away — roughly 4 feet — all 14 machines exceeded 50 decibels, the recommended noise limit for infants in hospital nurseries. Three of the machines were louder than 80 decibels, which, if played for more than eight hours, would exceed the recommended noise exposure for adults and could lead to noise-induced hearing loss, the study said. Thirteen of the machines exceeded the recommended noise limit even from 200 centimeters.

The researchers recommended that parents not use the machines’ maximum volume and keep them more than 200 centimeters — 6½ feet — from an infant.

BOTTOM LINE: Some ambient sound machines designed to help infants sleep might damage their hearing.

CAUTIONS: The study did not assess actual use of the machines around infants, or whether they led to actual hearing loss.